Circuit interrupter



Dec. 17, 1957 J, MlKos 2,816,994

CIRCUIT INTERRUPTER Filed Nov. 4, 1955 United States Patent @ffice e 2,816,994 Patented Dec. 1 7, 1 957 CIRCUIT INTERRUPTER John J. Mikos, Highland Park, Ill., assignor to S & C

Electric Company, Chicago, Ill., a corporation of Delaware Application November 4, 1955, Serial No. 545,044 18 Claims. (Cl. 200-149) This invention relates, generally, to electric circuit interrupters and it has particular relation to construction of trailers for use in load interruptor devices such as shown in United States Patent No. 2,591,950, issued April 8, 1952, and in application Serial No. 493,083, led March 9, 1955.

Among the objects of this invention are: To provide a trailer construction that is simple and eicient in operation and which can be readily and economically manufactured and installed; to construct the trailer in such manner that it is capable of withstanding shocks to which it may be subjected in moving from one position to another; to employ a high strength insulating rod extending through a tubular member capable of evolving an are extinguishing medium due to the heat of an arc for moving the tubular member conjointly with a movable contact to which the rod is connected; to insure that the entire trailer comprising the rod and tubular member will move from one operative position to another even though a portion of the tubular member should become detached from the remainder; and to reinforce the rod where it is connected to the movable contact.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiments thereof shown in the accompanying drawing and it comprises the features of construction, combination of elements and arrangement of parts that will be exemplified in the constructions hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of this invention reference can be had to the following detailed description, taken together with the accompanying drawing, in which:

Figure 1 is a longitudinal vertical sectional view of an l auxiliary circuit interrupter in which the present invention is embodied;

Figure 2 is a vertical sectional view, at an enlarged scale, of the trailer assembly shown in Figure 1;

Figure 3 is a fragmentary View showing a modified construction for the upper end of the trailer assembly shown in Figure 2;

Figure 4 is another fractional view, similar to Figure 3, and showing still another modification; and

Figure 5 is a View, similar to Figure 2, showing a modified construction.

Referring now particularly to Figure 1 of the drawing, it will be observed that the reference character designates, generally, an auxiliary circuit interrupter which is shown in more detail in application Serial No. 493,083, filed March 9, 1955. The auxiliary circuit interrupter 1t) includes a tubular insulating housing 11 provided with an upper terminal, shown generally at 12, which is arranged to be connected to a stationary terminal of a disconnecting fuse or a disconnecting switch. Within the housing 11 is an inner insulating sleeve 13 which is movable relative thereto and is mounted on a conducting arm 14 that is arranged to be connected to the movable terminal of a disconnecting fuse or disconnecting switch for placing the auxiliary circuit interrupter 10 in shunt circuit relation with the terminals of the disconnecting fuse or disconnecting switch as the case may be.

Depending from the upper terminal 12 is a conductor rod 15 having a cam terminal 16 at its lower end and connected at its lower end by a flexible conductor 17 to a movable arcing terminal 18 having a central bore 18. The movable arcing terminal 18 engages a cylindrical contact assembly, shown generally at 19, that is carried by the conducting arm 14 and moves conjointly therewith and with the inner insulating sleeve 13.

Extending upwardly from the movable arcing terminal 18 an movable conjointly therewith is a tubular metallic sleeve 20 that is arranged to be engaged by a trigger 21 which is carried by the upper end of the inner insulating sleeve 13. When the upper terminal 12 and tubular insulating housing 11 are held stationary and the conducting arm 14 and inner insulating sleeve 13 are moved downwardly out of the lower end of the housing 11, the trigger 21 engages the upper end of the tubular metallic sleeve 20 and causes it to move downwardly conjointly with the inner insulating sleeve 13 thereby maintaining the movable arcing terminal 18 in engagement with the cylindrical contact assembly 19. As this movement takes place the flexible conductor 17 is extended and a coil spring 22, interconnecting the cam terminal 16 and the movable arcing terminal 18 is stressed until the trigger 21 engages the cam terminal 16 and is moved out of engagement with the upper end of the tubular metallic sleeve 20. Thereupon the spring 22 contracts and moves the arcing terminal 18 upwardly together with the tubular metallic sleeve 20. The arcing terminal 18 moves upwardly through a liner 23 of insulating material that evolves an arc extinguishing medium due to the heat of the arc and thus assists in extinguishing the same.

Depending from the movable arcing terminal 18 and movable conjointly therewith is a trailer stud or insulating rod 26 that is formed of high strength insulating material such as a glass lled polyester resin. The trailer stud or insulating rod 26 extends entirely through a trailer 27 in the form of a tubular member of insulating material that is capable of evolving an arc extinguishing medium when subjected to the heat of the arc. Preferably the trailer 27 is formed of methyl methacrylate resin as is the liner 23. However, it will be understood that other arc extinguishing materials can be employed which have the required electrical and mechanical characteristics.

As shown more clearly in Figure 2 of the drawing the trailer stud or insulating rod 26 fits loosely in an opening or bore 28 in the trailer 27. As there shown the diameter of the opening or bore 28 is slightly greater than the diameter of the trailer stud or insulating rod 26 to provide the loose fit. The upper projecting end 29 of the trailer stud or insulating rod 26 is of reduced diameter for receiving a metallic fitting 30 in the form of a reenforcing sleeve of metal such as aluminum. It Will be noted that the metallic fitting 30 is telescoped over the projecting end 29. An opening 31 extends transversely through the projecting end 29 and the metallic fitting 30 for receiving a pin 32, Figure 1, which flexibly secures the trailer assembly to the movable arcing terminal 18 with the end 29 and overlying fitting 30 telescoped within the bore 18. The reason for einploying the metallic fitting 30, here in the form of a sleeve of metal, is to reenforce the end 29 of the trailer stud or insulating rod 26 where it is connected to the movable arcing terminal 18. Preferably the metallic fitting 30 is secured by a suitable cement to the project- 3 ing end 29. This construction provides a strong and somewhat llexible coupling to the arcing terminal 18 in the confined space in the bore 18'.

As pointed out and is apparent in the drawing the trailer stud or insulating rod 26 extends entirely through the trailer 27. The reason for this construction is to make certain that even though the trailer 27 might become broken intermediate its ends, still it would move as a unit together with the movable arcing terminal l. lt will be appreciated that the trailer 27 is subjected to severe shock when the trigger 2l is released from the tubular metallic sleeve 20 and the spring 22 accelerates the arcing terminal 18 and the trailer 27 attached thereto during the circuit opening operation. Likewise, the trailer 27 is subject to severe shock when it is stopped at the end of its travel. Accordingly, the trailer stud or insulating rod 26 is connected to the trailer 27 at the end remote from the connection to the movable arcing terminal 18. This is accomplished by providing an enlarged opening or counterbore 33 at the lower end of the trailer 27 and securing a sleeve 34 of insulating material by suitable cement to the lower end of the trailer stud or insulating rod 26. Preferably the sleeve is formed of the same material as the trailer stud 25.

lt is desirable to provide a lluid tight seal between the trailer stud 26 and the trailer 27 in order to prevent the low through the bore 28 of the gaseous products of the arm. For this purpose a gasket 35 in the form of an O ring of rubber is provided at the base of the sleeve 34 which forms a head portion for the lower end of the trailer stud 26. The gasket 35 ts snugly with the outer surface of the lower end of the trailer stud 26 and with the surface of an annular groove 36 in the trailer 27.

The arc drawn on separation of the arcing terminal ld from the contact assembly 19 may impinge upon the metallic tting 3l) and cause erosion of the same. ln order to avoid this the construction shown in Figure 3 can be employed. lt will be observed that the arcing terminal 18 is provided with a contact tip 1S and that the end 29 of the trailer stud or insulating rod 26 projects therethrough into the central bore 1S of the arcing terminal 18. In order to prevent the arc drawn from the contact tip 1S" impinging upon the metallic sleeve and to protect it from the heat of the arc, a protecting sleeve 37 of are resisting, insulating and gas generating material, such as polyethylene, is provided around a reduced diameter portion 38 of the metallic sleeve 3d. It will be noted that the protecting sleeve 37 is telescoped over the reduced diameter portion 3S and n that it projects therewith into the adjacent end of the tubular member 27, the sleeve 37 itself extending into a counterbore 39. Not only does the sleeve 3'7 protect the underlying metallic sleeve 30 from erosion by the arc but also it evolves an arc extinguishing medium to repel the arc from its surface. In addition it prevents the application of heat from the arc and from Contact tip ld to the metallic sleeve 3) which otherwise would tend to injure the cement bond holding it to the end 29 of the stud or rod 26 and it cooperates with the sleeve 3d, Figure 2, forming the head portion for the insulao ing rod 26, to prevent relative endwise movement of the rod 26 and the sleeve 27. The sleeve 37 has a close fit with the surface of the counterbore T19 and thus provides a seal at the upper end of the bore 28 the lower end of which is sealed by the gasket 35. By thus protecting the projecting end 29 of the stud or rod 26 and the enclosing sleeve 30 the impact strength of the joint is maintained uuimpaired.

Figure 4 shows another modification of the upper end construction ot the trailer. It will be observed that a metallic fitting 4d in the form of a sleeve of aluminum is telescoped only part Way over the projecting end 29 of the insulating rod 26 and that it does not project out of the central bore 18' of the movable arcing terminal 18. Arranged in tandem on the projecting end 29 with the metallic sleeve 40 is a protecting sleeve 41 that is formed preferably of a ceramic material. It will be observed that the protecting sleeve 46 extends into the central bore 18' through the contact tip 18" and also that it telescopes into the counterbore 39 of the tubuar member 27 thereby completely enclosing the projecting end 29 and protecting the same from impingement by the arc 4drawn from the Contact tip 18. The sleeve di, like the sleeve 37, prevents the application of the heat of the arc to the end 29 of the stud or rod 26 and also it serves as a gas seal at the upper end of the bore 2S in the trailer 27.

ln the modification of the trailer construction shown in Figure 5 `a metallic fitting 42 in the form of a plug or insert of aluminum is employed. The metallic fitting 42 has a reduced diameter body portion or shank 43 which is telescoped within a bore 44 at the upper end of a trailer stud 26 which is otherwise similar in construction to the trailer stud 26 previously described. The body portion or shank 43 is secured in place in the bore 44 by a suitable cement.

At its upper end the metallic fitting 42 has a head d5 the diameter of which is the Same as the external diameter of the trailer stud 26. A transverse opening 46 extends through the head 45 for receiving the pin 32 when the trailer assembly is applied to the movable arcing terminal 18.

ln each of the embodiments of the invention shown in the drawing a relatively high strength stud or rod 26 is employed in conjunction with a relatively frangible trailer 27 in the form of a tube telescoped over the former. While the stud or rod 26 is relatively strong, it has little arc extinguishing properties. In contradistinction, the trailer 27, although frangible, has excellent arc excellent arc extinguishing characteristics. By combiuing the high strength stud or rod 26 with the frangible tubular trailer 27 capable of evolving a large quantity of an arc extinguishing medium, the advantages of both are obtained in a device that will tit into the limited space available in the circuit interrupter 10.

Since certain further changes can be made in the foregoing constructions and different embodiments of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawing and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. A trailer for connection to and movement with a contact of an electric circuit load interrupter device cornprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc and having the opening therethrough enlarged at one end, and an insulating rod having a head portion at one end interfitting with said enlarged opening at said one end of said tubular member and projecting out of the other end thereof for connection to said contact, said head portion together with the adjacent portion of said tubular member providing a mechanical connection therebetween at the end of said tubular member remote from said contact.

2. A trailer for connection to and movement with a contact of an electric circuit load interrupter device comprising, in combination, a tubular member formed of insulating material from the surface of which an Aarc extinguishing medium can be evolved due to the heat o-f an arc and having the opening therethrough enlarged at one end, an insulating rod having a head portion at one end intertting with said enlarged opening at said one end of said tubular member and projecting out of the other end thereof for connection to said contact, and a resilient gasket surrounding said rod at the base of said head portion and forming a seal between said rod and said tubular member to prevent the iiow therepast of uid products of the arc and providing a shock absorbing cushion therebetween, said head portion together with the adjacent portion of said tubular member providing a mechanical connection therebetween at the end of said tubular member remote from said contact.

3. A trailer for connection to and movement with a contact of an electric circuit load interrupter device comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc and having the opening therethrough enlarged at one end, an insulating rod having a head portion at one end intertting with said enlarged opening at said one end of said tubular member and projecting out of the other end thereof for connection to said contact, and a metallic iitting telescoped with said projecting end of said rod for reenforcing the same where it is to be connected to said contact.

4. A trailer for connection to and movement with a contact of an electric circuit loa-d interrupter device comprising, in combination, a tubular member formed of insulating material from the surface of which an are extinguishing medium can be evolved due to the heat of an arc and having the opening therethrough enlarged at one end, an insulating rod having an insulating collar secured thereto at one end to provide a head portion intertitting with said enlarged opening at said one end of said tubular member and extending out of the other end thereof for connection to said contact, an O-ring surrounding said rod at the base of said head portion and forming a seal between said rod and said tubular member to prevent the flow therepast of iiuid products of the arc and providing a shock absorbing cushion therebetween, and a metallic fitting telescoped with said projecting end of said rod for reenforcing the same where it is to be connected to said contact.

5. A trailer for connection to and movement with a contact of an electric circuit load interrupter device Comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing can be evolved due to the heat of an arc and having the opening therethrough enlarged at one end, an insulating rod having a head portion at one end interitting with and filling said enlarged opening at said one end of said tubular member and loosely fitting within and extending out of the other end thereof for connection to said contact, an O-ring surrounding said rod at the base of said head portion and forming a seal between said rod and said tubular member to prevent the flow therepast of fluid products of the arc, and a metallic fitting telescoped with said projecting end of said rod for reenforcing the same where it is to be connected to said contact.

6. A trailer for connection to and movement with a contact of an electric circuit load interrupter device comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an are and having the opening therethrough enlarged at one end, an insulating rod having a head portion at one end intertting with said enlarged opening at said one end of said tubular member and extending out of the other end thereof for connection to said contact, and a metallic sleeve telescoped over and secured to said projecting end of said rod for reenforcing the same where it is to be connected to said contact and having an opening extending transversely therethrough and through said projecting end to provide for the connection.

7. A trailer for connection to and movement with a contact of an electric circuit load interrupter device comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc and having the opening therethrough enlarged at one end, an insulating rod having a head portion at one end intertting with said enlarged opening at said one end of said tubular member and extending out of the other end thereof for connection to said contact, and a metallic plug having a body portion telescoped within and secured to said projecting end of said rod and a head portion provided with a transversely extending opening to provide for connection to said contact.

8. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, and an arc resisting insulating sleeve telescoped over said projecting end of said insulating rod and within said other end of said tubular member and adapted to extend into said central bore of said contact.

9. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, a metallic sleeve telescoped over and secured to said projecting end of said rod for reenforcing the same where it is to be connected in said central bore to said contact and having an opening extending transversely therethrough and through said projecting end to provide for the connection, and an arc resisting insulating sleeve telescoped over said projecting end of said insulating rod and within said other end of said tubular member and adapted to extend into said central bore of said contact.

10. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, a metallic sleeve telescoped over and secured to said projecting end of said rod for reenforcing the same where it is to be connected in said central bore to said contact and having an opening extending transversely therethrough and through said projecting end to provide for the connection, said metallic sleeve extending within said other end of said tubular member, and an arc resisting insulating sleeve telescoped over said metallic sleeve and within said other end of said tubular member and adapted to extend into said central bore of said contact.

ll. A trailer for connection to and movement with a contact for an electric circuit load interrupter device, said contact having a central bore, comprising, in cornbination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, a metallic sleeve telescoped over and secured to said projecting end of said rod for reenforcing the same where it is to be connected in said central bore to said contact and having an opening extending transversely therethrough and through said projecting end to provide for the connection, said metallic sleeve extending within said other end of said tubular member, and an arc resisting insulating sleeve telescoped over said metallic sleeve and within said other end of said tubular member and adapted to extend into said central bore of said contact, said one end of said tubular member having a counterbore for receiving a head on said insulating rod and said other end of said tubular member having a counterbore for receiving said sleeve, said head and said sleeve cooperating with said insulating rod to prevent relative endwise movement of said tubular member thereon.

12. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, a metallic sleeve telescoped over and secured to said projecting end of said rod for reenforcing the same where it is to be connected in said central bore to said contact and having an opening extending transversely therethrough and through said projecting end to provide for the connection, said metallic sleeve extending within said other end of said tubular member, and an arc resisting insulating sleeve telescoped over said metallic sleeve in tandem relation to said metallic sleeve and within said other end of said tubular member and adapted to extend into said central bore of said contact.

13. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, a metallic sleeve telescoped over and secured to said projecting end of said rod for reenforcing the same where it is to be connected in said central bore to said contact and having an opening extending transversely therethrough and through said projecting end to provide for the connection, said metallic sleeve extending within said other end of said tubular member, and an arc resisting insulating sleeve telcscoped over said metallic sleeve in tandem relation to said metallic sleeve and within said other end of said tubular memoer and adapted to extend into said central bore of said contact, said one end of said tubular member having a counterbore for receiving a head on said insulating rod and said other end of said tubular member having a counterbore for receiving said sleeve, said head and said sleeve cooperating with said insulating rod to prevent relative endwise movement of said tubular member thereon.

14. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said Contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, and sealing means near each end of such tubular member forming seals between it and said rod to prevent the ilow therepast of fiuid products of the arc.

15. A trailer for connection to and movement with a contact of an electric circuit load interrupter device, said contact having a central bore, comprising, in combination, a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of an arc, an insulating rod extending through said tubular member and connected thereto at one end and projecting out of the other end for insertion in said central bore of said contact, and an arc resisting, gas evolving and heat resisting insulating sleeve telescoped over said projecting end of said insulating rod and within said other end of said tubular member and adapted to extend into said central bore of said contact.

16. An electric circuit load interrupter device compris` ing, in combination, separable contacts between which an arc is drawn on opening of the circuit, an insulating sleeve into which one of said contacts is drawn, and a trailer connected to and movable with said one contact into said sleeve and substantially filling the same, said trailer including a tubular member formed of relatively frangible insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of the arc, and a relatively high strength insulating rod extending into said one contact and through said tubular member and connected thereto at the end remote from said one contact whereby a mechanical connection is maintained with said tubular member in the event that it should become broken intermediate its ends.

17. An electric circuit load interrupter device comprising, in combination, separable contacts between which an arc is drawn on opening of the circuit, an insulating sleeve into which one of said contacts is drawn, and a trailer connected to and movable with said one contact into said sleeve and substantially filling the same, said trailer including a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of the arc, and an insulated rod extending through the principal part of said tubular member and projecting from one end into and connected to said one contact and mechanically connected to said tubular member remote from said one end whereby that principal part of said tubular member between said one end and the connection of said rod to said tubular member is conjointly movable with said rod in the event that the former should become broken intermediate the ends of said principal part.

18. An electric circuit load interrupter device comprising, in combination, separable contacts between which an arc is drawn on opening of the circuit, an insulating sleeve into which one of said contacts is drawn, and a trailer connected to and movable with said one Contact into said sleeve and substantially lling the same, said trailer including a tubular member formed of insulating material from the surface of which an arc extinguishing medium can be evolved due to the heat of the arc, an insulated rod extending through the principal part of said tubular member and projecting from one end into and connected to said one contact and mechanically connected to said tubular member remote from said one end whereby that principal part of said tubular member between said one end and the connection of said rod to said tubular member is conjointly movable with said rod in the event that the former should become broken intermediate the ends of said principal part, and a metallic litting telesco-ped with the projecting portion of said rod and with said one contact for reinforcing said projecting portion.

References Cited in the le of this patent UNITED STATES PATENTS 2,294,801 Rawlins Sept. 1, 1942 2,351,826 Lindell et al June 20, 1944 FOREIGN PATENTS 155,939 Austria Apr. 1l, 1939 

